1. Field of the Invention
This invention relates to a -motion transmission mechanism utilizing cam grooves and guide pins, and also relates to a low insertion force connector using this motion transmission mechanism. More specifically, the invention relates to a motion transmission mechanism and a low insertion force connector, in which the concentration of a stress on guide pins due to a notch effect is alleviated while achieving a compact design of the device.
2. Related Art
There is known a motion transmission mechanism in which cam grooves are formed in a driver (which imparts a motion to other member in the mechanism), and guide pins are formed on a follower (which is moved by the driver), and the guide pins are engaged respectively in the cam grooves, and such a motion transmission mechanism has been used in various mechanical devices and apparatuses.
In this motion transmission mechanism, when the driver is moved, the guide pins are moved along the respective cam grooves to thereby move the follower.
Such a motion transmission mechanism has heretofore been extensively used as a so-called low insertion force mechanism, and one example thereof is proposed in Japanese Patent Unexamined Publication Hei. 4-319271.
A low insertion force connector, disclosed in Japanese Patent Unexamined Publication Hei. 4-319271, will be described with reference to FIG. 5 which is an exploded, perspective view.
In this Figure, the conventional low insertion force connector comprises two male connectors 10A and 10B, a rectangular frame-like holder 20 for receiving the male connectors 10A and 10B, a female connector 30 for fitting on the male connectors 10A and 10B received in the holder 20, and a generally U-shaped slider 40 for inserting and withdrawing the male connectors 10A and 10B relative to the female connector 30.
Guide pins 121 and 121 are formed on each of upper and lower side walls of the holder 20, and insertion holes 31 and 31 are formed through each of opposite end walls of the female connector 30, and cam grooves 41 and 41 for respectively receiving the associated guide pins 121 on the holder 20 are formed in each of upper and lower side walls of the slider 40.
In the conventional low insertion force connector of the above construction, the slider 40 is inserted into a predetermined position in the female connector 30, and the guide pins 121 on the holder 20 are fitted respectively in the cam grooves 41 in the slider 40.
Then, when the slider 40 is pushed into the female connector 30, the guide pins 121 are moved respectively along the cam grooves 41, so that male connectors 10A and 10B, received in the holder 20, are fitted into the female connector 30.
In the above conventional low insertion force connector, the boundary between the holder 20 and each guide pin 121 is an angle portion 121b as shown in FIG. 6(a), and therefore when the slider 40 is slid, a notch effect is produced, and more specifically a stress, imparted to the guide pin 121 by the cam groove 41, concentrates on the angle portion 121b, which results in a problem that the strength is reduced.
Therefore, in order to alleviate the concentration of the stress on the guide pin due to the notch effect, there has heretofore been used a method in which the proximal end portion of a guide pin 122 is chamfered to form a radiused (curved) portion 122b.
As shown in FIGS. 7(a) and 7(b), the conventional guide pin 122 comprises a pin body 122a, substantially serving as a guide, and the radiused portion 122b for alleviating the stress.
In order that the pin body 122a can substantially serve as the guide, the pin body 122a must have a length equal to that of the guide pin 121 shown in FIG. 6(a).
Therefore, the length of projecting of the guide pin 122 is increased by an amount equal to the height of the radiused portion 122b, which results in a problem that the overall size of the low insertion force connector is increased.
In the case where a large stress is applied to the guide pin 122, it is necessary to increase the length of the pin body 122a and also to increase the size of the radiused portion 122b, and therefore there is encountered a problem that the overall size of the low insertion force connector is more increased.
And besides, a clearance, equal to the height of the radiused portion 122b, is formed between the slider 40 and the holder 20 (that is, the surface from which the guide pin 122 projects), and therefore when the slider 40 is slid, a load is concentrated on those surfaces of each guide pin 122 and the associated cam groove 41 which are held in sliding contact with each other, and this results in a problem that an abnormal sound is produced by the friction between the guide pin and the cam groove.